1. Field of the Invention
The present invention relates to a data recovery system and method thereof, more specifically, to a data recovery system and method thereof capable of outputting corresponding binary signals in response to various patterns.
2. Description of the Related Art
When an optical disc drive reads a high-density optical disc such as a Blue-ray Disc (BD) and a High Density-Digital Versatile Disk (HD-DVD), a maximum-likelihood (ML) detector, for example a Viterbi decoder, is widely used for overcoming an inter-symbol interference (ISI) (interference between reproduced signals corresponding to bits recorded adjacent to each other) for data recovery. For a low-density optical disc, a non-maximum-likelihood detector, e.g. a data slicer, is commonly used on account of non-critical ISI. As for a medium-density disc, e.g. a Digital Versatile Disk (DVD), the non-maximum likelihood detector was mostly utilized in the past. However, in recent years, for raising capability of data recovery for a recordable/rewritable DVD, the maximum likelihood detector is applied in the optical disc drive.
Theoretically, maximum likelihood detector is a widely used technique for increasing the capability of data recovery. In fact, due to present day advancement in the recordable/rewritable DVD and a rapid advancement of recording/rewriting speed for the optical disc drive, reproducing signals corresponding to bits recorded adjacent to each other on a disc may realize some special patterns not complying with channel responses of the maximum likelihood detector. Such special patterns reduce capability of data recovery and increase the data error rate for the maximum likelihood detector. However, such special patterns may result in better data recovery capability for the non-maximum likelihood detector. Despite re-designing the maximum likelihood detector, a solution to improve the capability of data recovery for reading such special patterns will inevitably lead to a complex maximum likelihood detector.